Touch interfaces are used in a variety of computer systems. FIG. 1A depicts a side view of a portion of a conventional touch interface 10 in the absence of a user's touch. The conventional touch interface 10 includes a screen 20, emitter 30, and detector 40. Although only one emitter 30 and one detector 40 are depicted, the conventional touch interface 10 typically includes emitters on first and second sides of the screen 20 and corresponding detectors on the third and fourth sides of the screen 20 that are opposite to the first and second sides, respectively.
In operation, the emitter 30 emits an electromagnetic signal that is typically an infrared signal. The infrared signal follows the path 50 to the detector 40 in the absence of a user's touch. When a user is not touching the screen 20, the detector 40 detects the infrared signal. Thus, infrared signals between the emitters and detectors form a grid over the screen 50 when a user is not touching the screen 20.
FIG. 1B depicts the conventional touch interface 10 when a user touches the screen 20. When the user touches the screen 20, the path 50 of the infrared signal is changed to the path 50′. Thus, because path 50′ does not reach the detector 40, the infrared signal does not reach the detector 40. As a result, the user's touch is detected. A touch that interrupts any of the infrared signals between the emitter and detector pairs will be detected. Thus, the conventional touch interface 10 allows the user to interact with the computer system employing the conventional touch interface 10.
Referring to FIGS. 1A and 1B, although the conventional touch interface 10 functions, one of ordinary skill in the art will readily recognize that the conventional touch interface 10 is subject to detecting false positives for unintentional touches. Unintentional touches occur when items other than a user touch the screen. Unintentional touches can interrupt the path 50 between the emitter 30 and detector 40. For example, items other than the user depicted in FIG. 1B can result in the path 50′ that does not reach the detector 40. For example, clothing such as ties, flies, or other items touching the screen 20 result in the path 50′. Consequently, the conventional touch interface 10 detects such unintentional touches, resulting in false positives for the unintentional touches.
Accordingly, what is needed is a mechanism for providing a touch interface that reduces the false positives that are detected. The present invention addresses such a need.